CARACAS (Reuters) - While the streets of the affluent east of the Venezuelan capital Caracas overflowed with protesters during a recent anti-government march, no-one demonstrated in the west side’s 23 de Enero slum.

Residents of the poor hillside neighborhood instead watched from their windows and sidewalks as groups of armed, black-clad men wearing balaclavas rode motorbikes through their streets.

Venezuela’s opposition calls such shows of force by so-called colectivo groups an intimidation tactic to prevent protests in Caracas’ poorer west end communities that have long been a stronghold of the Socialist government.

In the face of such threats, slum residents who oppose Venezuela’s unpopular Socialist leader are organizing behind closed doors. They hold discrete meetings in apartments and offer social services to those suffering from the country’s brutal economic crisis.

They say that winning the support of Venezuela’s traditionally pro-government poor could prove a tipping point for the opposition as it seeks general elections, freedom for jailed activists and autonomy for the opposition-controlled National Assembly.

“As these armed groups are threatening us here, opposition supporters must express themselves in clandestinity,” said Celia Fernandez, an activist with the hardline opposition Popular Will party who lives in 23 de Enero.

“How do we do politics? We call it ‘having a coffee.’ We visit up to 40 houses a day,” she said. “That’s how we organize ourselves to go to marches or bang pots at night, which you have to do with the lights off because they can shoot you or threaten your family.”

At least 65 people have died in protests, riots, and lootings across the oil-rich nation since early April, with gunmen blamed for deaths on both sides.

Colectivo members reject accusations that they use scare tactics and violence. They describe themselves as defenders of the legacy of late leftist leader Hugo Chavez and point to their charity work.

While the colectivos have spooked some anti-government supporters, the opposition says it has made significant inroads in the once fiercely “Chavista” slums which they feared to enter prior to the 2013 election of President Nicolas Maduro.

Some opposition-affiliated groups have launched initiatives in poor Caracas neighborhoods to provide food to schoolchildren left hungry by chronic shortages - services once offered by government agencies when high oil prices swelled state coffers.

“DON‘T PLAY WITH FOOD”

“Up until 2013, we couldn’t even enter many areas in La Vega,” said Esteban Farias, a member of the Justice First opposition party that works in the poor Caracas neighborhood through a non-profit called Mi Convive or “My Buddy”, which also organizes sports activities.

“Here we’re doing a healthy form of politics, from a social point of view, and we’ve advanced quite a bit in poor areas,” Farias said standing inside a soup kitchen in La Vega, one of seven the organization operates in poorer parts of Caracas.

Staple products like milk and rice are running short or are so expensive that they are out of the reach of the poor, a problem that has steadily turned the government’s backers against Maduro.

“I really believed in Chavismo, it was ‘fatherland or death’ for me,” said Jaqueline Arguinzone, 51, speaking in the hallway of her home in 23 de Enero, which partially collapsed due to heavy rains this year.

“So many bad things have happened in the last few years that I didn’t believe in anyone. But in these people, yes. They’re young people with a new vision,” she said, pointing to a group of Justice First activists offering to help her clear the hallway.

The shift has been reflected in elections, too. While the ruling Socialist Party won seven of nine National Assembly seats in Caracas in 2010, it only pocketed one in the 2015 vote when the opposition swept to victory.

To help rebuild its popularity, Maduro’s government launched a food distribution system last year, known as CLAP, in which Venezuelans can buy a subsidized food bag once a month.

Opposition activists say that too is being used to stifle dissent, such as the beating of pots and pans - a traditional Latin American protest known as a ‘cacerolazo.’

“We don’t do cacerolazos in my area. They reached a deal to avoid putting the CLAP bags at risk,” said Farias, in reference to opposition supporters and organizers of the food distribution system.

Other areas of La Vega are venting anger at the government through cacerolazos, even though they know they may get cut from CLAP.

“People aren’t accepting this anymore. You can’t play with food,” said Farias.